An electrical interconnect, channel or transmission line may be characterized for various electrical characteristics over a range of transmission frequencies or signaling rates. Characterization may include measuring or modeling electrical characteristics such as insertion or return loss for transmission lines having a differential connection. Some characterization techniques employ large matrixes of frequency domain data to model electrical characteristics. For example, a cable to be used as an electrical interconnect may require around 120,000 measured or modeled values for each differential connection. If the modeled cable includes a 4-pair model, over 1,000,000 values may be required. A high number of values may be needed because time domain conversion is how model data is typically used. Time domain conversion usually requires a very large bandwidth of finely sampled frequency domain points to characterize a transmission line.